Thermal Performance and Morphological Variation of Diceraeus melacanthus (Hemiptera: Pentatomidae) Under Controlled Rearing

The neotropical green-belly stink bug, Diceraeus melacanthus (Dallas, 1851), is considered a major pest of maize and wheat production systems in South America, particularly under no-tillage systems and soybean–maize crop succession. Given the influence of climate change on arthropod development, this study aimed to characterize the effect of five constant temperatures (16, 21, 26, 31, and 36 °C) on the morphometrics and weight variations of D. melacanthus across all developmental phases. The experiment was conducted under controlled laboratory conditions ((14-10 h L-D photoperiod; 65±15% relative humidity) using a completely randomized design. Morphometric parameters, including total body length, pronotum width, abdomen width, rostrum length, and humeral angle length, were measured alongside fresh weight (mg). Results indicated that the thermal range of 26-31 °C represents the physiological optimum, promoting maximum growth and biomass accumulation, with adults reaching a significantly higher mean weight (67.9 mg) at 31 °C. Conversely, temperatures of 21 °C and 36 °C acted as limiting factors, significantly reducing abdominal width and humeral angle development, particularly in the fourth and fifth instars. Individuals reared under laboratory conditions exhibited larger morphometric values than those previously reported for field populations, likely due to the high-quality, diversified diet provided. The high phenotypic plasticity exhibited across the 16-36 °C gradient underscores the resilience of D. melacanthus to climatic fluctuations, enabling its year-round persistence in agricultural fields. These findings provide essential biological parameters for improving population growth models and strengthening Integrated Pest Management (IPM) strategies under future climate scenarios.